1. Field of the Invention
The present invention relates to a information processing apparatus that includes a non-volatile main memory unit and a data recovering method.
2. Description of the Related Art
Recently, development of a technology related to non-volatile memories such as a flash memory, a magneto-resistive random access memory (MRAM), a ferroelectric random access memory (FeRAM), and a phase change random access memory (PRAM) is in progress. In the non-volatile memory, recorded data cannot be lost even if a power outage occurs. It is anticipated that in the future, the non-volatile memory will be a substitute for a volatile memory such as a dynamic random access memory (DRAM) that is presently widely used as a main memory in computers.
If such a non-volatile memory is used as the main memory in the computers, data saved in the main memory or a status of a system will not be lost even if the power outage occurs in the main memory during processing of computer programs. The data stored in the main memory or the status of the system will be retained in the main memory. Due to this, when power is restored, computer operations can be easily restarted from a status at the time of the power outage, thus shortening activation time of the computers and enhancing operability. In the non-volatile memory, which differs from the volatile memory, a power supply device is not required for maintaining stored contents. Thus, reduction in power consumption of the entire computer, miniaturization of a battery, and longevity of the battery can be anticipated.
In an existing technology disclosed in JP-A 2005-107573 (KOKAI), when power is restored after sudden power outage in the computer that uses such non-volatile memory, interruption is notified to a central processing unit (CPU) by using a power monitoring mechanism for maintaining and restoring the status at the time of the power outage. The status of the CPU is saved in the main memory unit by using control software that is similar to an operating system.
However, in the technology described in JP-A 2005-107573 (KOKAI), when power is restored after sudden power outage, to restore a volatile system status such as a processor status, it is necessary to secure power when storing the system status in a non-volatile memory (hereinafter, “non-volatile main memory unit”) at sudden power outage. For this reason, batteries such as additional capacitors are required. In other words, the batteries are not required for maintaining the system status stored in the non-volatile main memory unit, however, the batteries are required for storing the system status at sudden power outage. Generally, the battery used in the computer for concluding the writing process is a secondary battery. Thus, insufficient power is likely to be supplied if the power outage occurs frequently.
For adequate power supply even at the time of sudden power outage, battery capacity can be increased by using bigger batteries. By using the non-volatile main memory unit, it is anticipated that the batteries that are indispensable for volatile memory can be made compact or eliminated. However, providing bigger batteries to cope up with sudden power outage contradicts the earlier anticipation.